objective-c - 如何在 Mac 中使用 AVCaptureStillImageOutput 捕获屏幕

Question

我想捕获Mac的屏幕，并且我知道AVCaptureStillImageOutput可以工作。但我不知道如何在Mac中使用它。

我希望有人能给我一些有关使用该类捕获屏幕的示例代码。或者一些建议也可以。

下面的代码是在IOS设备中使用AVCaptureStillImageOutput来捕获图片。也许可以修改并在Mac中使用？

感谢任何帮助，提前致谢。

/////////////////////////////////////////////////
////
//// Utility to find front camera
////
    /////////////////////////////////////////////////
    -(AVCaptureDevice *) frontFacingCameraIfAvailable{
    NSArray *videoDevices = [AVCaptureDevice
    devicesWithMediaType:AVMediaTypeVideo];
    AVCaptureDevice *captureDevice = nil;

    for (AVCaptureDevice *device in videoDevices){

      if (device.position == AVCaptureDevicePositionFront){

        captureDevice = device;
        break;
    }
}

//  couldn't find one on the front, so just get the default video device.
if (!captureDevice){

    captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
}

return captureDevice;
}

/////////////////////////////////////////////////
////
//// Setup Session, attach Video Preview Layer
//// and Capture Device, start running session
////
/////////////////////////////////////////////////
-(void) setupCaptureSession {
AVCaptureSession *session = [[AVCaptureSession alloc] init];
session.sessionPreset = AVCaptureSessionPresetMedium;

AVCaptureVideoPreviewLayer *captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer    alloc] initWithSession:session];
[self.view.layer addSublayer:captureVideoPreviewLayer];

NSError *error = nil;
AVCaptureDevice *device = [self frontFacingCameraIfAvailable];
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
if (!input) {
    // Handle the error appropriately.
    NSLog(@"ERROR: trying to open camera: %@", error);
}
[session addInput:input];

self.stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys: AVVideoCodecJPEG, AVVideoCodecKey, nil];
[self.stillImageOutput setOutputSettings:outputSettings];

[session addOutput:self.stillImageOutput];

[session startRunning];
}

/////////////////////////////////////////////////
////
//// Method to capture Still Image from 
//// Video Preview Layer
////
/////////////////////////////////////////////////
-(void) captureNow {
AVCaptureConnection *videoConnection = nil;
for (AVCaptureConnection *connection in self.stillImageOutput.connections) {
    for (AVCaptureInputPort *port in [connection inputPorts]) {
        if ([[port mediaType] isEqual:AVMediaTypeVideo] ) {
            videoConnection = connection;
            break;
        }
    }
    if (videoConnection) { break; }
}

NSLog(@"about to request a capture from: %@", self.stillImageOutput);
__weak typeof(self) weakSelf = self;
[self.stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error) {

     NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];
     UIImage *image = [[UIImage alloc] initWithData:imageData];

     [weakSelf displayImage:image];
 }];
    }

Answer 1

听起来您想截屏。

这是我在 iOS 中用来拍摄整个 View 的图片 (screenCapture)，

UIView *wholeScreen = self.view;

// define the size and grab a UIImage from it
UIGraphicsBeginImageContextWithOptions(wholeScreen.bounds.size, wholeScreen.opaque, 0.0);
[wholeScreen.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *screengrab = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

我不知道这是否适用于 OSX。

编辑 - 好吧，上面的方法不起作用，也许你可以看看这是否可以帮助你，ScreenShot Apple Docs

这里是关于其作用的描述 - 使用 Quartz Display Services 获取包含任何连接的显示器内容的图像。还允许用户将图像保存到磁盘上的文件中。